JS之mouseover和mouseenter

Posted 2020-08-05

mouseenter事件只会触发一次，触发对象是注册对象或者注册对象的子元素

mouseover事件可以触发多次，触发对象是注册对象或者注册对象的子元素

 

<p>不论鼠标指针穿过被选元素或其子元素，都会触发 mouseover 事件。</p>  
    <p>只有在鼠标指针穿过被选元素时，才会触发 mouseenter 事件。</p> 
    <div class="over" style="background-color:lightgray;padding:20px;width:40%;float:left">  
        <h2 style="background-color:white;">被触发的 Mouseover 事件：<span></span></h2>  
    </div>  
    <div class="enter" style="background-color:lightgray;padding:20px;width:40%;float:right">  
           <h2 style="background-color:white;">被触发的 Mouseenter 事件：<span></span></h2>  
    </div>  
    <script>
        var x = 0,y = 0;
        var div1 = document.getElementsByClassName("over")[0];
        div1.addEventListener("mouseover",function(){
            var span = this.getElementsByTagName("span")[0]
            span.innerText = (x +=1);
            span.style.cssText = "border:2px red solid;";
        },false);
        
        var div2 = document.getElementsByClassName("enter")[0];
        div2.addEventListener("mouseenter",function(){
            var span = this.getElementsByTagName("span")[0]
            span.innerText = (y +=1);
            span.style.cssText = "border:2px red solid;";
        },false);
    </script>